Marumo Júlio T, Isiki Vera L K, Miyamoto Hissae, Ferreira Rafael V P, Bellini Maria H, de Lima Luis F C P
Instituto de Pesquisas Energéticas e Nucleares--IPEN-CNEN/SP, Av Professor Lineu Prestes, 2242 Cidade Universitária, São Paulo, CEP 05508-000, Brazil.
Radiat Environ Biophys. 2008 Feb;47(1):131-7. doi: 10.1007/s00411-007-0130-3. Epub 2007 Sep 9.
Radioactive lightning rods were manufactured in Brazil until 1989, when the licenses for using radioactive sources in these products were lifted by the national nuclear authority. Since then, these rods have been replaced by the Franklin type and collected as radioactive waste. However, only 20% of the estimated total number of installed rods has been delivered to the Brazilian Nuclear Commission. This situation causes concern, since there is the possibility of the rods to be disposed as domestic waste. In Brazil, 64% of the municipal solid waste is disposed at garbage dumps without sufficient control. In addition, (241)Am, the radionuclide most commonly employed, is classified as a high-toxicity element, when incorporated. In the present study, (241)Am migration experiments were performed by means of a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as common solid waste. (241)Am sources removed from lightning rods were placed inside lysimeters filled with organic waste that was collected at the restaurant of the Instituto de Pesquisas Energéticas e Nucleares. The generated leachate was periodically analyzed, and characteristics such as pH, redox potential, solid content and the concentration of the radioactive material were determined. The equivalent dose for members of the public was calculated considering ingestion of contaminated drinking water as the major path of exposure. Estimated doses were about 20-times below the effective dose limit of 1 mSv year(-1) for members of the public as recommended by the International Commission on Radiological Protection. This suggests the radiation risk caused by lightning rods disposed at uncontrolled garbage dumps to be low. It should be noted, however, that the number of investigated lightning rods was quite small. The results of this study might therefore not be entirely representative and should be interpreted with care. They provide, however, a very first basis for characterizing the transfer of (241)Am from lightning rods to the human food chain.
放射性避雷针在巴西一直生产到1989年，当时国家核管理机构取消了这些产品使用放射源的许可。从那时起，这些避雷针已被富兰克林型避雷针取代，并作为放射性废物收集。然而，估计已安装避雷针总数中只有20%已交付给巴西核委员会。这种情况令人担忧，因为这些避雷针有可能被当作生活垃圾处理。在巴西，64%的城市固体废物被倾倒在垃圾场，且没有充分的管控。此外，最常用的放射性核素（241）镅在被人体摄入时被归类为高毒性元素。在本研究中，通过渗滤计系统进行了（241）镅迁移实验，以评估当作普通固体废物处理的放射性避雷针造成污染的风险。从避雷针上取下的（241）镅源被放置在装有从能源与核能研究所餐厅收集的有机废物的渗滤计内。定期分析产生的渗滤液，并测定其pH值、氧化还原电位、固体含量和放射性物质浓度等特性。考虑到摄入受污染的饮用水是主要暴露途径，计算了公众成员的当量剂量。估计剂量比国际放射防护委员会建议的公众成员有效剂量限值1 mSv年−1低约20倍。这表明倾倒在无管控垃圾场的避雷针造成的辐射风险较低。然而，应该指出的是，所调查的避雷针数量相当少。因此，本研究结果可能并不完全具有代表性，应谨慎解读。不过，它们为表征（241）镅从避雷针向人类食物链的转移提供了首个基础。
